Thread by @danicalir

Ok, #dayofscience break time! Let’s talk about research and throwing rocks down hills.

Here’s Carleton undergrad Sara Wall helping me drop 600 lbs of rocks and collect photogrammetry data in the Oregon Coast Range last year.

Why? First, a little backstory...
(thread)

When geomorphologists predict how landscapes will erode and evolve, we’re usually averaging over pretty long timescales (>1000s of years) and large areas (>100s of square miles). The equations and models we use are good at capturing changes at these scales!
#dayofscience

But if you zoom in to smaller scales, many of the natural processes that move sediment and cause erosion—like tree throw!—are actually pretty irregular and some just aren’t described accurately by the physics in our model frameworks.
#dayofscience

Right now, we mostly use equations that describe the ground surface as a continuous layer of material all slowly “creeping” downhill. But in many places, especially steep ones, soil doesn’t just creep—it tumbles, slides and bounces over the surface!
#dayofscience

My recent work is on this kind of sediment transport, especially after wildfires, which can quickly release sediment trapped behind plants. Once it travels downhill, that sediment enters streams, where it can cause water quality problems and bulk up debris flows!
#dayofscience

Our models can’t really account for these processes or predict how landscapes will change if they occur more often—which is a big concern, especially in the western US, where climate change is causing more wildfires & hazards (like the 2018 Montecito debris flows).
#dayofscience

So how does this all lead to throwing rocks down hills? We’re working on a new model to describe sediment transport across scales! To use it, we need to understand the physics connecting rock motion to measurable things like rock size and ground slope or roughness.
#dayofscience

It turns out that the distance our rocks are likely to travel is surprisingly well represented by a very simple model whose parameters scale with rock size, ground slope & roughness—these control how much kinetic energy rocks gain or lose as they travel downhill!
#dayofscience

One of our key take-aways is that surface roughness really matters for hazards & sediment budgets! When wildfires burn away vegetation and smooth the ground, larger rocks can travel downslope WAY farther and faster, which could lead to more destructive debris flows.
#dayofscience

More broadly, my group’s research focuses on quantifying the connections between geomorphic processes and landscape evolution across scales and under changing conditions. This will allow us to better understand the impacts of climate change, human impacts + hazards.
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To do this, we use a combination of field experiments and observations, data-driven interdisciplinary techniques like terrestrial lidar scanning and seismic monitoring, computational analysis and modeling, and quantitative theory development.
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We’re also building a schmancy gamma spectroscopy lab, where we’ll be able to analyze 7Be, 137Cs, 210Pb and other radionuclides to examine erosion rates over modern timescales!
#dayofscience

Right now, though, I’m doing none of these things. I’m in my office trying to finish two papers, and I’m in need of coffee. On that note, back to work!
#dayofscience

PS. I’m sharing my research and experiences as a new assistant professor this #dayofscience to fundraise for @ESWNtweets @GirlsWhoCode and @SWEtalk.

If you can make a donation, please support #womeninSTEM!
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